Apply Winter Mulch Now
Marginally cold-hardy plants can be completely covered with loose mulch materials. |
There are a few factors to consider when setting up
your favorite plants to survive the coming winter weather.
One important factor is whether the plants can
handle the winter weather in your area’s USDA cold hardiness zone. In Oklahoma,
for example, there are three cold hardiness zones. The southeast part of the
state is zone 7b, the panhandle and Miami are zone 6a, but, Tulsa is 7a and
Bartlesville is 6b.
There are also microclimates on your property. For
example, the south side of the house is warm enough to protect a wider range of
perennials than the north side. Containers on a west-facing porch are more
sheltered than containers out in the middle of a bed.
For the most part, plants that are native to your
USDA growing zone (www.plants.usda.gov/) will do better no matter how harsh the
winter is. But, as we have seen, drought with record cold temperatures can
change everything.
Applying winter mulch will help hedge your bets,
preventing wind damage, soil heaving from freeze and thaw, or drought drying of
roots. In addition, the plants we love that are not quite cold hardy in our
zone benefit from receiving an extra level of care.
Newly planted perennials such as trees and shrubs
must be protected for the winter if you want them to perform at their best next
spring.
Do not fertilize or prune once freezing weather has
arrived. The new growth you stimulate will make the entire plant vulnerable to
cold, dry, weather. Weak and diseased plants should be removed on sunny days
that allow working outside.
Evergreens suffer the most during a winter drought. If
there is no rain for a few weeks, water the plants in your garden that retain
their color in winter. This is especially true of young evergreens.
When your area has had a killing frost (4 hours of
32-degrees F), it is time to apply mulch around perennials you want to thrive
next year, including those in containers.
Mulch should be applied 6 to 8 inches away from
trunks and ground-hugging stems. The volcano shaped mulch you often see hugging
tree trunks can become home to insects, mice and other creatures that eat bark
during the winter.
Mulches can be made of pine needles, tree bark,
compost, cotton seed hulls, cotton burr, straw, sawdust, pecan shells, or grass
clippings. These are called organic mulch. Non-organic or synthetic mulch materials,
such as shredded rubber, can be used although they do not add anything to
improving the soil over time.
Large mulch particles such as tree bark and pecan
shells allow rain to enter the soil. Sawdust, grass clippings, cotton seed
hulls and compost insulate the ground better but rain cannot sink down as well.
Two inches of fine compost is plenty while 5 inches
of straw is necessary to provide the same freeze protection.
Do not use leaves unless they were shredded in the
mower or previously composted. Never use leaves or stems from diseased plants
in your compost or as mulch.
Organic mulches break down over the winter, improving
the soil, increasing its ability to hold moisture, and supporting beneficial
insects next growing season.
Roses benefit from being winter-mulched with a pile
of loose material stacked taller than the graft. For example if the graft is 6 inches
above the soil line, the mulch should be 8 inches tall.
Marginally cold-hardy plants in our area, such as
gardenias, camellias, rhododendrons, canna lily and calla lily benefit from
being completely covered by loose mulch. In the photo our gardenias are covered
with pine straw.
In
Oklahoma it is recommended that you remove mulch around the first of March.
See OSU HLA-6404 for more details.
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